Near-Edge X-Ray Absorption Fine Structure of Ultrananocrystalline DiamondHydrogenated Amorphous Carbon Films Prepared by Pulsed Laser Deposition

Abstract EN

The atomic bonding configuration of ultrananocrystalline diamond (UNCD)/hydrogenated amorphous carbon (a-C:H) films prepared by pulsed laser ablation of graphite in a hydrogen atmosphere was examined by near-edge X-ray absorption fine structure spectroscopy.

The measured spectra were decomposed with simple component spectra, and they were analyzed in detail.

As compared to the a-C:H films deposited at room substrate-temperature, the UNCD/a-C:H and nonhydrogenated amorphous carbon (a-C) films deposited at a substrate-temperature of 550∘C exhibited enhanced π∗ and σ∗C≡C peaks.

At the elevated substrate-temperature, the π∗ and σ∗C≡C bonds formation is enhanced while the σ∗C–H and σ∗C–C bonds formation is suppressed.

The UNCD/a-C:H film showed a larger σ∗C–C peak than the a-C film deposited at the same elevated substrate-temperature in vacuum.

We believe that the intense σ∗C–C peak is evidently responsible for UNCD crystallites existence in the film.